NATICA. 
257 
Great Oolite, on the other hand, the round-shouldered forms show some increase, 
so that the Buspiroid forms have not so full a possession of the field as is the case 
in the Inferior Oolite ; though such species as Eusjpira Sharpei and Euspira 
pijramidata are very pronounced. 
The following diagnosis will comprehend all the Haticidge of the Inferior 
Oolite with the exception of one rare species. These species are nowhere 
abundant, save Natica Bajocensis locally, and with one notable exception they are 
of medium size. 
Genus — Natica ; Section A. — Buspiroid or sub-Buspiroid. 
Shell globular, or sub-globular, thick ; spire short or elevated, always in steps ; 
lohorls more or less flattened posteriorly and mostly canaliculate. Columella thick and 
moderately encrusted, outer lip thin. Sometimes a narrow umbilical flssure. Aperture 
oval or semilunar, the longer axis ranging from half to three-quarters the total 
length of the shell. Spiral lines, rather ivide apart, may sometimes be traced. 
In this division there are forms (sub-Euspiroid) such as Natica globata, Natica 
Dundriensis, Natica Hulliana, and even Natica cincta, where the slope or modifica- 
tion of the sutural ledge (meplat) approaches the round-shouldered species. 
Hence the difficulty of drawing the line. 
In the Lower Division of the Inferior Oolite and generally rather low down is 
a group of medium-sized shells, of yrhxch. Natica adducta may be taken as the type. 
This group comprises Natica adducta, with N. Oppelensis and N. globata as 
varieties, and Natica Lorieri, with N. proxima and N. canina as varieties. 
194. Natica adducta, Phillips, 1829. Type form, Plate XX, fig. 3. 
1829 and 1835. Natica adducta, Phil. Geol. Yorks., pt. 1, pi. ix, fig. 30. 
1851. — — — Morris and Lycett, Great Ool. Moll., p. 112, 
pi. XV, fig. 17. 
1852. — — — d’Orbigny, Terr, Jur,, ii, p. 189, pi. cclxxxix, 
figs. 4, 5. 
1882. — — — Hudleston, Geol. Mag., dec. 2, vol. ix, p. 199, 
pi. V, fig. 6. 
Bibliography, ^c. — The 'history of this wide-spread if not very common 
species has been slightly complicated owing to Phillips having given two different 
figures of Natica adducta, viz. pi. ix, fig. 30, and pi. xi, fig. 35. The former 
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